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Investigation of the Anisotropic Morphology-Induced Effects of the Slippery Zone in Pitchers of Nepenthes alata

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Journal of Bionic Engineering 2015年第1期12卷 79-87页

作者： pengfei zhang Huawei Chen Deyuan zhang School of Mechanical Engineering and Automation Beihang University Beijing 100191 China

Plant of carnivorous genus Nepenthes alata has evolved specific pitchers to prey insects for survival in the barren habitat, especially its slippery zone. The excellent slippery function has received considerable interest because of its potential applica- tion in antifriction surface design. The surface morphologies of intact and de-waxed slippery zones were characterized using scanning electron microscope and scanning white-light interferometer. Hierarchical structures with anisotropic micro- lunate structure and nano- wax crystals were found on the slippery zone. Due to the hierarchical structures, the slippery zone is hy- drophobic. It shows a significant anisotropic wettability with static contact angles 153.3° and 140.1° in the directions perpen- dicular and parallel to the upward direction （toward the peristome）, respectively. The sliding angles are -3° and -10° in the downward and upward directions, respectively. Crawling experiments indicate that the microscopic surface roughness and the brittleness of the wax crystals may reduce insect attachment in different modes according to the insect mass differences. Moreover, artificial slippery surfaces inspired by the slippery zone of Nepenthes alata were fabricated. Traction experiments quantitatively verified that the friction force of replicated lunate structures with Ra-2.54 μm surface roughness was reduced by about 25% as compared to flat surface with Ra-0.56 μm surface roughness for cricket claws.

关键词： biomimetic surface anisotropic wettability antifriction slippery surface Nepenthes alata

A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397

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Research in Astronomy and Astrophysics 2024年第1期24卷 285-291页

作者： Jiao Zheng pengfei zhang Li zhang Department of Astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China

Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is *** that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris.

关键词： gamma-rays:galaxies (stars:)pulsars:individual(PSR J1740-5340B) (Galaxy:)globular clusters:individual(NGC 6397)

Fabrication of Porous Si_3N_4-Lu_2Si_2O_7 Composite Ceramics

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Journal of Materials Science & Technology 2010年第5期26卷 449-453页

作者： pengfei zhang Litong zhang Xiaowei Yin National Key Laboratory of Thermostructure Composite Materials Northwestern Polytechnical University Xilan 710072China

To improve the corrosion resistance of porous Si3N4 used in the high temperature environments,which contain water vapor and volatile species,porous Si3N4-Lu2Si2O7 composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N 2 atmosphere at the temperatures lower than 1550 ° *** pores in ceramics were formed by removing the pore-forming agent（phenolic resin）.SiO2 derived by the oxidation of Si3N4 at 1250 ° C in air reacted with Lu2O3 at various sintering temperatures,leading to the formation of Lu2Si2O7 with excellent oxidation and corrosion *** phase composition,microstructure,and mechanical properties of the porous ceramics depended on the sintering ***3N4-Lu2Si2O7 composite ceramics with the porosity of 52% and the pore size of 0.2 μm were obtained by oxidation bonding at 1250 ° C for 1 h and pressureless sintering at 1550 ° C for 2 h using 4 wt pct Lu2O3 additive.

关键词： Porous ceramics Silicon nitride Lu2Si2O7 Pressureless sintering

Detection of Increasingγ-Ray Emissions from 4FGL J1718.5+4237 with Fermi-LAT

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Research in Astronomy and Astrophysics 2024年第8期24卷 169-174页

作者： Jiao Zheng pengfei zhang Li zhang Department of Astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China School of Physics and Engineering Technology Xingyi Normal University for NationalitiesXingyi 562400China

We report a gradual brighteningγ-ray source,4FGL J1718.5+4237,in 0.1-500.0 GeV,which may be associated with a blazar NVSS J171822+423948 with a redshift of~*** analyzed 15.25 yr ofγ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significantγ-ray emissions in the direction of the blazar with a test statistic(TS)of~*** on timing analysis using a 1 yr time bin,we have observed a gradual brightening inγ-ray emissions from the *** our analysis,we categorize them into two states:Quiet(TS~0)and Loud(TS~226)states,with the distinction occurring in 2016 August(MJD57602.69).From the Quiet state to the brightest period(the last data point),theγ-ray flux in 0.1-500.0 GeV increased by more than 12-fold from<0.2×10^(-8)photons cm^(-1)s^(-1)to 2.6×10^(-8)photons cm^(-1)s^(-1).Additionally,we studied the spectral properties in detail for the Loud state and the overall *** no significant variation was detected,both exhibited a spectral indexΓof~*** origin of the brighteningγ-ray emissions from the target is not yet *** long-term multi-wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.

关键词： galaxies active-blazars individual(4FGL J1718.5+4237)

Efimov effect in Dirac semi-metals

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Frontiers of physics 2018年第5期13卷 55-61页

作者： pengfei zhang Hui Zhai Institute for Advanced Study Tsinghua University Beijing 100084 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

The Efimov effect is defined as a quantum state with discrete scaling symmetry and a universal scaling factor. It has attracted considerable interests from nuclear to atomic physics communities. In a Dirac semi-metal, when an electron interacts with a static impurity through a Coulombic interaction, the same kinetic scaling and the interaction energy results in the Efimov effect. However, even when the Fermi energy lies exactly at the Dirac point, the vacuum polarization of the electron-hole pair fluctuation can still screen the Coulombic interaction, which leads to deviations from the scaling symmetry and eventually breaks down of the Efimov effect. This energy distortion of the Efimov states due to vacuum polarization is a relativistic electron analogy of the Lamb shift for the hydrogen atom. Motivated by the recent experimental observations in two- and three-dimensional Dirac semi-metals, we herein investigate this many-body correction to the Efimov effect and the conditions that allow some of the Efimov-like quasi-bound states to be observed in these condensed matter experiments.

关键词： Dirac semi-metal Efimov effect screening

Application of multi-stage dynamic magnetizing roasting technology on the utilization of cryptocrystalline oolitic hematite:A review

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International Journal of Mining Science and Technology 2022年第4期32卷 865-876页

作者： Hanquan zhang pengfei zhang Feng Zhou Manman Lu School of Resources and Safety Engineering Wuhan Institute of TechnologyWuhan 430205China

A large number of studies have shown that oolitic hematite is an iron ore that is extremely difficult to utilize because of its fine disseminated particle size, high harmful impurity content and oolitic *** recover iron from oolitic hematite, we developed a novel multistage dynamic magnetizing roasting technology. Compared with traditional magnetizing roasting technologies, this novel technology has the following advantages: firstly, the oolitic hematite is dynamically reduced in a multi-stage roasting furnace, which shortens the reduction time and avoids ringing and over-reduction;secondly, the novel dynamic magnetizing roasting technology has strong raw material adaptability, and the size range of raw materials can be as wide as 0–15 mm;thirdly, the roasting furnace adopts a preheating-heating process, and the low-calorific value blast furnace gas can be used as the fuel and reductant, which greatly reduces the cost. The actual industrial production data showed that the energy consumption in the roasting process can be less than 35 kg of standard coal per ton of raw ore. The iron grade of the concentrate and iron recovery reached 65% and 90%, respectively.

关键词： Oolitic hematite ore Magnetizing roasting Reduction kinetics Over-reduction Iron mineralogy

Scaling symmetry meets topology

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Science Bulletin 2019年第5期64卷 289-290页

作者： pengfei zhang Hui Zhai Institute for Advanced Study Tsinghua University

In 1970,Vitaly Efimov found an interesting phenomenon in a quantum three-body problem,which is now known as the Efimov *** found that when the two-body in teraction potential is short-ranged and is tuned to the vicinity of an s-wave resonance,an inhnite number of three-body bound states emerge and their eigenenergies En form a geometric sequence as En=-|Eo|exp(—2m/So).

关键词： Scaling symmetry meets topology In 1970

Preparing quantum states by measurement-feedback control with Bayesian optimization

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Frontiers of physics 2023年第6期18卷 291-299页

作者： Yadong Wu Juan Yao pengfei zhang Department of Physics Fudan UniversityShanghai 200438China State Key Laboratory of Surface Physics Key Laboratory of Micro and Nano Photonic Structures(MOE)Fudan UniversityShanghai 200438China Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China Shanghai Qi Zhi Institute AI TowerXuhui DistrictShanghai 200232China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China International Quantum Academy Shenzhen 518048China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Walter Burke Institute for Theoretical Physics&Institute for Quantum Information and Matter California Institute of TechnologyPasadenaCA 91125USA

The preparation of quantum states is crucial for enabling quantum computations and *** this work,we present a general framework for preparing ground states of many-body systems by combining the measurement-feedback control process(MFCP)with machine learning ***,we employ Bayesian optimization(BO)to enhance the efficiency of determining the measurement and feedback operators within the *** an illustration,we study the ground state preparation of the one-dimensional Bose−Hubbard *** BO,we are able to identify optimal parameters that can effectively drive the system towards low-energy states with a high probability across various quantum *** results open up new directions for further exploration and development of advanced control strategies for quantum computations and simulations.

关键词： state preparation feedback control Bayesian optimization

Scenario-oriented hybrid particle swarm optimization algorithm for robust economic dispatch of power system with wind power

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Journal of Systems Engineering and Electronics 2022年第5期33卷 1143-1150页

作者： WANG Bing zhang pengfei HE Yufeng WANG Xiaozhi zhang Xianxia School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China

An economic dispatch problem for power system with wind power is *** discrete scenario to describe uncertain wind powers,a threshold is given to identify bad scenario *** bad-scenario-set robust economic dispatch model is established to minimize the total penalties on bad scenarios.A specialized hybrid particle swarm optimization(PSO)algorithm is developed through hybridizing simulated annealing(SA)*** SA operators are performed according to a scenario-oriented adaptive search rule in a neighborhood which is constructed based on the unit commitment ***,an experiment is *** computational results show that the developed algorithm outperforms the existing algorithms.

关键词： wind power robust economic dispatch scenario simulated annealing(SA) particle swarm optimization(PSO)